LeetCode OJ:3Sum Closest

3Sum Closest

 

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

    For example, given array S = {-1 2 1 -4}, and target = 1.    The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

class Solution {public:    int threeSumClosest(vector<int> &num, int target) {        sort(num.begin(),num.end());          int ans=INT_MAX;        int dif=INT_MAX;        int n=num.size();          for(int i=0;i<n;i++){              for(int p1=i+1,p2=n-1;p1<p2;){                  int sum=num[i]+num[p1]+num[p2];                  if (abs(sum-target)<dif)                  {                      dif=abs(sum-target);                      ans=sum;                  }                  if (sum<target)                      p1++;                  else                      p2--;              }          }          return ans;      }};